My DQN is stuck and can't see where the problem is
After some research and reading this post, I see where my problem was: I was introducing a full consecutive batch of experiences, selected randomly, yes, but the experiences in the batch were consecutives.
After redoing my experience selection method, my DQN is actually working and has reached about +200 points after 400000 experiences (about 500 episodes; only 2-3 hours or training!). Before I couldn't reach that score after days of training.
I'll let it train to see if there are something I can improve. Thanks to everyone who tried to help me! I let this answer here just in case someone has the same problem as me.